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Scientists have discovered a sub-atomic particle they believe is crucial in the formation of the universe.

The Higgs boson, otherwise known as the God particle, is thought to give all other particles in the universe their mass.

Scientists in Geneva and Melbourne say the discovery still needs to be verified, but it is the strongest evidence yet that the particle exists.

The particle is "consistent with (the) long-sought Higgs boson", the European Organisation for Nuclear Research (CERN) said in a statement.

Scientists have wrestled with the elusive particle for nearly half a century.

"We have reached a milestone in our understanding of nature," said CERN director general Rolf Heuer.

"The discovery of a particle consistent with the Higgs boson opens the way to more detailed studies, requiring larger statistics, which will pin down the new particle's properties, and is likely to shed light on other mysteries of our universe."

Finding the Higgs would validate the Standard Model, a theory which identifies the building blocks for matter and the particles that convey fundamental forces.

It is a hugely successful theory but has several gaps, the biggest of which is why some particles have mass and others do not.

Mooted by British physicist Peter Higgs in 1964, the boson is believed to exist in a treacly, invisible, ubiquitous field created by the Big Bang 13.7 billion years ago.

When some particles encounter the Higgs, they slow down and acquire mass, according to theory. Others, such as particles of light, encounter no obstacle.

Extensive search

The discovery was announced simultaneously in Geneva and in Melbourne, where the international High Energy Physics conference is taking place.

Extensive and expensive testing has been conducted in a quest to either prove or disprove the existence of the Higgs boson.

CERN led the search but have been hesitant to announce their results in case of statistical flukes.

In scientific parlance, the goal was "five sigma", meaning that there is just a 0.00006 per cent chance that what the two laboratories found is a mathematical quirk.

Because the Higgs boson cannot be seen, scientist had to infer its existence. The process has been likened to proving the existence wind - it cannot be seen, but we know that it exists from the effect it has on other things.

This inference is done by smashing protons together at in the CERN's Large Hadron Collider, a massive 27 kilometre-long particle accelerator that lies beneath the Franco-Swiss border near Geneva.

Inside the underground tunnel, scientists created tiny but fierce collisions that caused sub-atomic debris to fly into detectors that were built into the 360-degree walls of a car-sized lab.

Scientist then sifted through the signals of the collisions and look for patterns that point to the existence of the Higgs boson.